How to use psutil.Popen with unicode commands on Python 2
The issue is your use of double-quotes when defining command. The way it's written splits the statement into multiple strings in all the wrong places. Substituting single-quotes for the first and final quotes (open and close of string) fixed the issue for me.
command = u'\"C:\\Program Files (x86)\\Microsoft Office\\root\\Office16\\EXCEL.EXE\" \"{}\"'.format(full_path)